JP3101976B2 - Automatic needle thread feeder of sewing machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic needle thread feeding device for a sewing machine.

(Prior art) In a conventional automatic thread tension sewing machine, an upper thread feeding means is disposed between an upper thread supply source and a balance in accordance with sewing conditions, and a required amount of upper thread in accordance with the sewing conditions is reduced. Supplies have been proposed. Inputting or detecting the cloth feed amount, the needle amplitude amount, the cloth thickness, etc. of the sewing conditions, calculates the theoretically necessary thread amount, and calculates the theoretically necessary thread amount from the upper thread supply source during a phase other than the thread tension by the balance. The balance which pays out the upper thread by the feeding means, and which has conventionally carried out and tightened the upper thread, only tightens the seam.

(Problem to be Solved by the Invention) In such a conventional needle thread feeding means, the thread feeding amount is a theoretically necessary thread amount determined by the aforementioned sewing conditions. However, in actual sewing, there are other sewing conditions which are difficult to convert into data as a selection input or a detection input.

For example, data of the frictional force given to the feed efficiency between the cloth and the feed dog of the cloth feeder. For a cloth with a small frictional force and slipperiness, the feed amount of the sewing condition for theoretically obtaining the thread requirement and the actual cloth feed The amount differs.

In addition, the cloth thickness of the input value of the sewing condition for theoretically obtaining the required amount of the thread varies depending on the pressure of the presser foot, which causes a difference from the actual required amount of the upper thread.

In addition, due to differences in sewing conditions, such as differences in slip resistance of cloth or thread, thread elongation, etc., which make input data difficult, the upper thread may be insufficiently tightened due to excessive supply of upper thread at the stitch after sewing.
Insufficient supply of upper thread causes excessive tightening, preventing proper upper thread supply.

Therefore, an object of the present invention is to provide an automatic needle thread feeding device that can cope with the above-mentioned sewing conditions that are difficult to convert into data.

(Means for Solving the Problems) Therefore, in the present invention, a needle that moves up and down, a needle thread supplementing means that forms a lockstitch in cooperation with the needle, and a needle that is timed to move up and down the needle. A sewing machine provided with a balance that moves up and down, a thread tension applying device that is interposed between the balance and the upper thread supply source and that intermittently applies tension to the upper thread in synchronization with the vertical movement of the needle. Gripping the upper thread between a driving roller connected to a stepping motor disposed between the thread tension applying device and the balance, and a driven roller abutting a driven roller abutting the driving roller; Needle thread feeding device for feeding a needle thread from a supply source, and calculating means for calculating a theoretically necessary thread amount based on input values or detection values of sewing conditions and calculating a supplied needle thread feeding amount smaller than the calculated value And the supply of the calculation result of the calculation means And stepping motor control means for controlling the driving amount of the stepping motor so as to correspond to the amount.

(Operation) Information which can be converted into data of sewing conditions, for example, information such as a feed amount, an amplitude value, an amplitude direction, a cloth thickness, and a thread thickness is selected or detected and input, and a theoretically necessary thread amount is calculated. Calculate a supply needle thread feed-out amount that is smaller than the theoretically necessary thread amount by a certain ratio from the calculation result, and increase the supply needle thread feed-out amount between the driving roller and the driven roller to a relaxation phase other than the upper thread tightening phase of the balance. The yarn is paid out, and the shortage is pulled out in a state where tension is applied from the upper thread supply source by the yarn tension applying device by the upper thread tightening action of the balance.

Example Next, an example of the present invention will be described in detail with reference to the drawings. FIG. 3 is an external view of the sewing machine, which will be described with reference to FIG.

An upper shaft 2 to which rotation is transmitted by being connected to a drive unit (not shown) fixed to the sewing machine frame 1 is rotatably supported, and a needle bar 3 connected to the upper shaft moves left and right and A needle 17 is fixed to the tip of the needle bar so as to be vertically movable. A needle plate 18 is fixed to the sewing machine frame 1 below the needle, and a needle hole for inserting the needle 17 and the needle bar 3 are provided.
And a feed dog groove in which the feed dog 19 driven in the front-rear direction orthogonal to the left-right movement of the feed tooth is formed. Reference numeral 20 denotes a shuttle serving as a needle thread supplementing means, which forms a lockstitch seam below the needle plate 18 in cooperation with the needle 17.

The needle bar 3 is connected to a needle bar amplitude stepping motor 4 (not shown) fixed in the sewing machine frame 1 via a transmission means. It is connected to a stepping motor 5 (not shown) for feeding adjustment fixed in the machine frame 1.

The pattern seam is formed by driving the needle bar amplitude stepping motor 4 in synchronization with the rotation of the upper shaft 2 to drive the needle bar 3
The feed stitching motor 5 is driven in synchronization with the rotation of the upper shaft 2 to adjust the amount of forward / backward movement of the feed dog 19 to form a pattern seam.

Reference numeral 6 denotes a front panel fixed to the front of the sewing machine frame 1, on which a pattern selection key 7 is arranged as a pattern selecting means for selecting a desired pattern from the stored multiple patterns. Have been.

Reference numeral 8 denotes a display unit for displaying a selected pattern, which is constituted by a liquid crystal display. Reference numeral 9 denotes a manual adjusting means for adjusting the predetermined needle bar amplitude and feed amount to desired amounts. Of these, 10 is an amplitude adjustment key, and the amplitude adjustment is enabled by selection, the amplitude is increased by operating the increase key 10a, and the amplitude is decreased by operating the decrease key 10b. The amplitude amount is displayed on the manual amplitude value display means 11. Numeral 12 is a feed adjustment key, the feed amount adjustment is enabled by selection, the feed amount is increased by the increase key 12a, the feed amount is reduced by the decrease key 12b, the manual feed amount, the feed amount adjusted by the display means 13 is adjusted. It is configured to display.

Reference numeral 15 denotes a known balance, which includes the needle 17 and the upper thread supply source 16.
2 (see FIG. 2), and is connected to the upper shaft 2 via connecting means, and is configured to move up and down in synchronization with the up and down movement of the needle 17.

Reference numeral 21 denotes a known cloth presser, which is detachably attached to a lower end of a presser bar 22 which is supported on the sewing machine frame 1 so as to be vertically movable, and a presser bar holder 23 is fixed above the presser bar. ing. Reference numeral 24 denotes a presser adjusting screw which is screwed into a screw hole provided in the sewing machine frame 1 and is mounted so as to be vertically adjustable. A coil spring 25 is disposed between a lower end of the presser adjusting screw and an upper end of the presser bar holder 23, and always presses the presser bar holder 23 downward to move the cloth presser 21 to the feed dog.
A known holding mechanism for pressing the cloth 19 and gripping the cloth during this time to feed the cloth is provided.

Next, the cloth thickness detecting means will be described with reference to FIG. 6 and FIG. Reference numeral 26 denotes an engagement pin,
It is stuck to. 27 is a potentiometer,
A release arm 28 is fixedly attached to the sewing machine frame 1 and a detection shaft 27a of the potentiometer 27. One end of the release arm is formed with a forked portion 28a, and the forked portion is fitted to the engaging pin 26. Reference numeral 14 denotes a presser lift, which is rotatably fitted to a pin 29 fixed to the sewing machine frame 1.

Next, a first embodiment of the needle thread feeding means will be described with reference to FIG.

In the figure, reference numeral 16 denotes a bobbin of the upper thread supply source. A thread tension applying device 30 is constructed as shown in FIG. 4, and has a thread tension plate 31 fixed to one end thereof, a thread tension shaft 32 supported by a support plate 35 on the sewing machine frame 1, and a thread tension shaft 32. A thread pressing plate 34 which is fitted to the tension shaft so as to be movable in the axial direction and cooperates with the thread tension plate 31 so as to be able to clamp the upper thread 33, and a thread formed on the shaft portion of the thread tension shaft 32. Pressing body 36 which is screwed and has a projection 36a on the outer periphery
And a thread tension spring 37 which is disposed between the pressing body and the thread pressure plate 34, always presses the thread pressure plate against the thread tension plate 31, and applies pulling resistance to the upper thread 33 sandwiched therebetween. A groove 38a in which the protrusion 36a of the pressing body 36 is axially movable by being rotatably fitted to the thread tension shaft 32 so that the axial movement thereof is restricted.
And a thread tension dial 38 that forms a scale on the outer periphery.

Reference numeral 39 denotes a release lever, which is rotatably fitted to a pin 40 fixed to the sewing machine frame 1 and has one end provided with the thread tension plate.
It is arranged below the contact position between the yarn pressing plate 31 and the yarn pressing plate 34. The other end of the release lever 39 is formed with a claw portion 39a, and a spring means is provided on the outer periphery of the cam portion of the release cam 41 fixed to the upper shaft 2.
It is in contact with the bias of 42. A small diameter portion 41a and a large diameter portion 41b are formed on the outer periphery of the cam portion of the release cam 41. When the distal end of the release lever 39 is in contact with the large-diameter portion, the release lever is at a position where the release lever has rotated counterclockwise and the other end is in contact with the thread tension plate 31 and the thread pressing plate 34. It is located below the contact. When the tip of the release lever 39 comes into contact with the small diameter portion 41a of the release cam 41 by the rotation of the upper shaft 2, the release lever rotates clockwise, and the other ends are the thread tension plate 31 and the thread pressing plate. Invaded from below between 34 and
The thread pressing plate is moved in the axial direction against the urging of the thread tension spring 37 to release the upper thread 33 from being held.

Reference numeral 43 denotes a needle thread feeding device, which will be described with reference to FIG. A support pin 45 is fixed to a holding plate 44 which is fixed to the sewing machine frame 1.
Are integrally fitted.

Reference numeral 47 denotes a needle thread feeding stepping motor, which is fixed to the holding plate 44, and a gear 48 is fixed to an output shaft 47a of the needle thread feeding stepping motor 47.
The gear and the gear 46a of the rotary cylinder 46 are fitted.

Reference numeral 49 denotes a drive roller which is fitted in the rotary cylinder 46, and has a roller groove 49a formed therein so as to enable the ball roller 50 to be disengaged. Reference numeral 51 denotes a holder for holding the ball roller 50. 52 is an engagement spring,
The ball roller is disposed between the wall of the roller 49a and the ball roller 50, and constantly presses the ball roller toward the inclined portion on the small clearance side of the roller groove 49a formed in the counterclockwise rotation direction. Therefore, when rotating the rotating cylinder 46 in the counterclockwise direction, the ball roller 50 is moved to the narrow side of the roller groove 49a of the driving roller 49, and the rotating cylinder 46 and the driving roller 49 are integrated. And rotate.

On the other hand, when rotating the rotating cylinder 46 clockwise, or when rotating the driving roller 49 counterclockwise while fixing the rotating cylinder, the ball roller 50 is pressed against the engagement spring 52 to prevent the ball roller 50 from being pressed. The drive roller 49 moves to the wall side of the roller groove 49a,
A so-called one-way clutch which releases the connection between the rotary cylinder 46 and the rotary cylinder 46 and independently rotates.

Numeral 53 denotes a rotation amount detecting means of the driving roller 49, which is constituted by a rotating plate 54 fixed to the driving roller 49 and forming a plurality of slits and a photo interrupter 55.

Reference numeral 56 denotes an upper thread gripping device, and a gripping lever 58 is rotatably fitted on a lever shaft 57 fixed to the sewing machine frame 1. One end of the holding table 60 is rotatably fitted to a pin 59 fixed to one end of the holding lever.A pin 61 is fixed to the holding table, and driven rollers 62 and 63 are rotatably fitted to the pin. ing. A driven roller on the upper thread supply source side among the driven rollers
62 is formed of an elastic material effective for gripping the upper thread at the time of feeding by the rotation of the drive roller 49, and the driven roller 63 on the balance 15 side corresponds to sliding friction when the thread is pulled out by the balance 15. Further, the drive roller 49 is formed of the same kind of metal material.

Reference numeral 64 denotes a gripping spring, which is disposed between the sewing machine frame 1 and one end of the gripping lever 58, and urges the gripping lever to rotate counterclockwise. By the rotation of the grip lever, the grip table 60 moves in the direction of arrow A,
The gripper rotates with respect to the pin 61 such that the driven rollers 62 and 63 abut on the driving roller 49.

The tip of the release arm 28 is configured to move in the direction of arrow B by the rotation of the presser lifting lever 14. The release arm 28 may be connected to the lifting lever 14.

Next, a control device of the sewing machine according to the present invention will be described with reference to FIG. 1 of a system block diagram.

66 is a central processing unit to which the pattern selection key 7 and the selected pattern display means 8 are connected.

A pattern data storage means 67 stores display data of a pattern corresponding to the pattern selection key 7 and pattern stitch forming data, and is connected to the central processing unit 66.

A selected pattern storage means 68 stores the pattern selected by the pattern selection key 7.

Numeral 69 denotes an upper shaft phase detecting means, as shown in FIG. 8, a rotating plate 70 fixed to the upper shaft 2 and forming a plurality of slits.
And a photo-interrupter fixed to the sewing machine frame 1
71 and is formed.

The needle bar amplitude stepping motor 4 for the amplitude operation of the needle bar 3 and the feed adjustment stepping motor 5 for adjusting the feed amount of the feed dog 19 are connected to the central processing unit via a stepping motor drive circuit 72. It is connected to the device 66.

A sewing machine motor 73 fixed to the sewing machine frame 1 and connected to transmit power to the upper shaft 2 is connected to the central processing unit 66 via a sewing machine motor drive circuit 74.

Numeral 75 denotes a rotational speed detecting means of the sewing machine, which comprises a rotational speed detecting plate 76 fixed to the upper shaft 2 and a speed detecting photo-interrupter 77 similarly to the rotating plate 70 of the upper shaft phase detecting means 69. .

The central processing unit 66 is connected to the needle thread feeding stepping motor 47 via a needle thread feeding stepping motor driving circuit 78. The rotation amount detecting means 53
Is connected to the central processing unit 66.

Numeral 79 is a needle thread feeding amount calculation program storage means, which is the needle bar amplitude and feed amount data of the pattern stitch forming data stored in the pattern data storage means 67 and the potentiometer 27 which is a cloth presser detecting means. A program for calculating a theoretically necessary thread amount and a needle thread feed-out amount using the cloth thickness data from the controller is stored.

Reference numeral 80 denotes a shortage thread amount storage means,
Stores the difference between the detected amount of the rotation amount detecting means 53 that detects the amount of the upper thread drawn from the upper thread supply source 16 due to the rotation of the upper thread supply source 16 and the amount of the upper thread fed by the stepping motor 47 for feeding the upper thread. Means.

Next, the operation of the present invention will be described with reference to FIG. By operating the pattern selection key 7, the selected pattern is stored in the selected pattern storage means 68. The presser bar 22 is raised by operating the presser lift 14 (FIG. 7), a cloth is guided between the cloth presser 21 and the needle plate 18, and the presser lift 14 is again operated to operate the presser lifter. Presser bar
Lower 22 to grip the cloth.

The upper phase of inserting the cloth under the presser foot 21 is
17 is the uppermost position, and the balance 15 is a lower position before the top dead center of the balance.

For the first stitch, the needle bar amplitude stepping motor 4 is operated based on the first stitch data of the pattern stitch formation data of the pattern selected by operating the pattern selection key 7 to set the first stitch to the needle drop position.

Next, the sewing machine motor 73 is driven by operating a starting means (not shown). The upper shaft 2 connected to the sewing machine motor
Rotates, and the needle 17 descends from the top dead center position.

The detected phase is input from the upper shaft phase detecting means 69 with the rotation of the upper shaft 2. When the detection phase is a predetermined specific phase and the extension phase, the claw portion 39a of the release lever 39 is in contact with the small diameter portion 41a of the release cam 41 fixed to the upper shaft 2 by the bias of the spring means 42. The release lever
39 is a position rotated clockwise, the other end of the release lever intrudes from below between the thread tension plate 31 and the thread pressure plate 34, and biases the thread pressure plate by the thread tension spring 37. To release the pinching of the upper thread 33.

The release of the pinch allows the upper roller to be fed by the drive roller 49. The release phase is a phase after the feed dog 19 is immersed from the upper surface of the needle plate 18. In this phase, using the cloth thickness information indicated by the output value of the potentiometer 27, using the needle thread feeding amount calculation program stored in the needle thread feeding amount calculation program storage means 79, theoretically the required amount of thread, From the theoretically necessary yarn amount, a supply upper yarn feeding amount smaller by a specific amount S is calculated. The specific amount S is an amount that fluctuates under the influence of other sewing conditions that are not input and is a value determined in advance by an experimental value. The supply amount of the supplied needle thread as a result of the calculation drives the needle thread stepping motor 47 to rotate the gear 48 fixed to the output shaft 47a. The gear 46a of the rotary cylinder 46 meshes with the gear, and rotates counterclockwise about the support pin 45. Due to the rotation of the support pin, the ball roller 50 moves the roller groove 50 of the drive roller.
The drive roller and the rotary cylinder are integrally engaged with each other and rotate in a counterclockwise direction to grip between the driven rollers 62 and 63 by the bias of the grip spring 64. Thread 3
3 is fed out from the upper thread supply source 16. The operation for feeding out is carried out during the phase before the feed dog 19 rises above the upper surface of the needle plate 18, for example, in the upper thread relaxing state before the balance 15 goes up.

In the above-mentioned feeding phase, the data of the second stitch is read out from the pattern data storage means 67, and the feed adjusting stepping motor 5 is driven according to the feed data to feed the stitch amount for forming the stitch of the second stitch. The settings are made.

As described above, in the phase where the feed dog 19 is raised, the needle
Since the tip of the needle 17 is also substantially above the upper surface of the needle plate 18, the needle bar amplitude data in the data of the second needle described above is read out and the needle bar amplitude stepping motor 4 is driven to drive the second needle. Needle drop position.

After the phase in which the upper thread supply stepping motor 47 is driven and the upper thread supply is completed, the claw portion 39a of the release lever 39 comes into contact with the large diameter portion 41b of the release cam 41, and the release lever 39 is released. By rotating in the counterclockwise direction, the distal end of the release lever is rotated downward from the entry position between the thread tension plate 31 and the thread pressing plate 34.

By the movement of the release lever, the thread pressing plate 34 abuts on the thread pressing plate 31 by the pressing of the thread tension spring 37, and clamps the upper thread 33 therebetween.

The supply amount of the supplied upper thread which is driven from the drive roller 49 by driving the upper thread feeding stepping motor 47 is a fixed ratio smaller than the theoretically necessary thread amount as described above. In the phase before the top dead center, the upper thread supplied for forming the seam is insufficient. The shortage is given a tension through the upper thread feeding device 43 and the thread tension applying device 30 by raising the balance 15, pulled out from the upper thread supply source 16, and reduces the necessary amount together with the seam thread tightening. The first stitch is formed by supplying the stitch.

The drive roller 49 of the upper thread feeding device 43 forms a one-way clutch with the rotary cylinder 46.

A gear 49a of the rotary cylinder and a gear 48 fixed to an output shaft 47a of the needle thread feeding stepping motor 47 mesh with each other, and the rotary cylinder is in a state where the needle thread feeding stepping motor 47 is excited. Since the driving roller 49 does not rotate and the upper thread 33 is sandwiched between the driven roller 63 and the driven roller 63, the driving roller 49 rotates counterclockwise with respect to the upper thread withdrawal caused by raising the balance 15. Upon receiving the force, the engagement of the ball roller 50 between the roller groove 49a and the rotary cylinder 46 is released, and the driving roller 49 does not provide resistance to pulling out the upper thread 33. The driven roller 62 is in contact with the driving roller and rotates together. This shortage of the withdrawal amount is detected by the rotation amount detection means 53 and stored in the shortage thread amount storage means 80.

Next, the cloth on which the first stitch is formed is transferred by the feed amount set in accordance with the feed data of the second stitch of the stitch forming data until the above-described specific phase, and the cloth is moved in accordance with the amplitude data of the second stitch. The needle 17 is moved to the second needle drop position by driving the needle bar amplitude stepping motor 4.

In a specific phase in which the feed dog 19 is located below the upper surface of the needle plate 18, the release lever 39 is again rotated clockwise to be held between the thread tension plate 31 and the thread pressing plate 34. The upper thread 33 is released. Using the cloth thickness information detected by the potentiometer 27 in this specific phase, the needle amplitude information and the feed amount information in the stitch forming data previously read out from the pattern data storage means 67, the needle thread feeding amount is calculated. The amount of thread theoretically required is calculated by the upper thread feeding amount calculation program stored in the calculation program storage means 79.

Next, a value obtained by multiplying the shortage yarn amount stored in the shortage yarn amount storage means 80 by a specific ratio is subtracted from the theoretically necessary yarn amount as a specific yarn amount to calculate a supply upper yarn feeding amount. The specific rate is multiplied by a value determined because elements that are not theoretically included in the calculation of the required thread amount, such as cloth and yarn, are the same after the first stitch.

Next, the upper thread feeding stepping motor 47 is driven to hold the upper thread 33 between the driving roller 49 and the driven rollers 62 and 63 to carry out the feeding. In this feeding phase, the feed data of the third stitch is read out from the pattern data storage means 67, and the feed adjusting stepping motor 5 is driven to set the feed amount for forming the stitch of the third stitch. After the phase in which the feeding is completed, the claw portion 39a of the release lever 39 comes into contact with the large-diameter portion 41b of the release cam 41, and rotates the release lever 39 counterclockwise. From the intrusion position between the plate 31 and the thread pressing plate 34, it rotates downward. The upper thread 33 is clamped between the thread tension plate 31 and the thread pressing plate 34 by the movement of the release lever.

During the subsequent phase up to the top dead center of the balance, the above-described supply thread feed amount is set to be smaller than the required actual stitch amount, so that the thread tension is applied to the thread tension applying device 30 by raising the balance 15. The shortage of the upper thread 33 is drawn from the upper thread supply source 16 while rotating the drive roller 49 which is provided and is constituted by a one-way clutch of the upper thread feeding device 43. This shortage of the withdrawal amount is detected by the rotation amount detection means 53 and stored in the shortage thread amount storage means 80.

The cloth on which the second stitches have been formed is transported by the feed amount set in accordance with the feed data of the third stitch of the stitch formation data before the above-described specific phase, and the needle 17 is moved to the third position.
The needle bar amplitude stepping motor 4 is driven in accordance with the stitch amplitude data to determine the third stitch drop position.

In the specific phase in which the feed dog 19 is lowered and located below the upper surface of the needle plate 18, the release lever 39 rotates clockwise again to move the feed lever 19 between the thread tension plate 31 and the thread pressing plate 34. The upper thread 33 to be clamped is released.

In this specific phase, the cloth thickness information detected by the potentiometer 27 and the calculation data consisting of the amplitude data and the feed data in the stitch formation data read from the pattern data storage means 67 are stored in the upper thread feeding amount calculation program storage. The calculation is performed according to the calculation program stored in the means 79 to theoretically calculate the required amount of thread.

Next, the shortage thread amount stored in the shortage thread amount storage means 80 is read out, and this is subtracted from the theoretically necessary thread amount as a specific minus thread amount to calculate the supply thread advance amount.

Next, the upper thread feeding stepping motor 47 is driven to hold the upper thread 33 between the driving roller 49 and the driven rollers 62 and 63 to carry out the feeding.

Also, the feed amount data in the stitch forming data of the fourth stitch is read out from the pattern data storage means 67, and the feed adjusting stepping motor 5 is driven to set the feed amount for forming the stitch of the fourth stitch. . After the phase in which the feeding is completed, the release lever 39 rotates counterclockwise to clamp the upper thread 33 between the thread tension plate 31 and the thread pressing plate 34.

During the subsequent phase up to the top dead center of the balance, the above-described supply thread advance amount is set to be smaller than the required actual stitching amount, so that the thread tension is applied to the thread tension applying device by raising the balance 15. Then, the drive roller 49 constituted by a one-way clutch of the upper thread feeding device 43 is rotated to draw out the insufficient thread amount from the upper thread supply source 16. The insufficient upper thread amount of the third stitch is compared with the insufficient upper thread amount of the second stitch stored in the insufficient upper thread amount storage means 80, and when it is larger than the second needle and a separately determined minimum withdrawal amount. Is the third
The insufficient upper thread amount is updated to the insufficient upper thread amount and
To memorize.

Thereafter, the stitch is formed by continuing the fourth and fifth stitches.

The relationship between the theoretically necessary yarn amount and the supply upper yarn payout amount will be described with reference to FIG.

In the figure, D indicates the theoretical thread required amount, S indicates the minus upper thread amount for the assumed factor, G indicates the supply upper thread feeding amount, R indicates the actual stitch required amount, and U indicates the insufficient upper thread amount. If 10 pulses are required for driving 1 mm, theoretically the required thread amount D _{1 at} the first stitch is 5 mm and minus the upper thread amount for the assumed factor at the start of 50 pulses.
A case of the 20 pulses S ₁ at 2.0 mm and feed on the yarn feed amount G ₁ is feeding is 30 pulses at 3.0 millimeters,
They lack the amount of yarn U ₁ during stitch formation the actual seam required amount to be 18 pulses at 1.8 millimeter R ₁ becomes 4.8 mm. And 1.8 mm deficiency on the amount of yarn U _1, 18 pulses are withdrawn being tensioned.

In the second stitch, the theoretical yarn requirement D ₂ is 10 mm
0 pulse, but lack the amount of yarn U ₁ of the first stitch of 18 pulses at 1.8 millimeters, since it is required that you in the starved than always actual seams necessary amount of supply on the yarn feed amount, experimental Specific ratio 0.5 separately determined as optimal around 0.5
Multiplied by updating the negative on the yarn amount S ₂ for assumed factors 0.9 millimeter 9 pulses. This is the purpose of the present invention, which is to provide optimal tightening to any seam, and when the yarn is tensioned while leaving a shortage of yarn supply at the time of the last drawing at the time of forming each seam. It is to be withdrawn from the yarn supply. Accordingly supplied on line release G ₂ is 9.1
If the assumed factor in forming the stitch is the same as that of the first stitch, the actual stitch required amount R ₂ fR ₂ = D
_2- (D _1- R ₁ ) 98 pulses at 9.8 mm from insufficiency
U ₂ F0.7 millimeter 7 less than the first stitch of 1.8 millimeter 18 pulses of the upper thread shortage U ₁ described above is a pulse, the minimum withdrawn amount U _0, for example, 0.2 millimeter 2 pulses of U ₀ is here defined separately and since greater than, and updates and stores the shortage on the yarn amount U ₁ stored in the shortage on Itoryou storage unit 80 runs out on the yarn amount U _2, and the lack of the amount of yarn U ₂ The supply needle thread unwinding amount
Storing actual seams required amount R ₂ plus and G _2.

The third theory yarn required amount D ₃ in stitch is 70 pulses at 7 mm and 0 negative on the yarn amount S ₃ for assumed factors before S _2.
9mm 9 supply the yarn feed amount G ₃ using pulsed 7-0.9
= 6.1 millimeters 61 pulses are delivered.

Actual seams required amount R ₃ if assumed factors during stitch formation identical to the second stitch is R ₃ = D ₃ - a (D ₂ -R ₂₎ in the determined 6.8 millimeter 68 pulses.

The lack of the amount of yarn U ₃ since a 0.7 millimeter 7 pulses. The lack of the amount of yarn U ₃ is set to the same if the same is assumed factors mentioned above.

Then theoretically yarn required amount D ₄ in the fourth stitch is 10 millimeters 10 pulses, minus the amount of yarn S ₄ for assuming factors of previous S ₃
Calculating a supply on the yarn feed amount G ₄ with 0.9 millimeter 9 pulses. A 9.1 millimeter 91 pulse feeding by G ₄ = 10-0.9 = 9.1. Second needle is assumed factors during stitch formation, if the same as the third needle actual seams required amount R ₄ is R ₄ = D ₄ - a 9.8 millimeter 98 pulses obtained in (D ₃ -R _3). For this reason, the shortage thread amount U ₄ is
It becomes 0.7 millimeter 7 pulses. In this embodiment, the theoretical thread requirement is calculated for each stitch. However, when the desired pattern is selected by operating the pattern selection key 7, the theoretical thread requirement is calculated in advance. The calculation result may be stored in the selected pattern storage means 68 in a readable manner together with the selected pattern.

Further, in the present embodiment, the case where the minus upper thread amount S for the assumed factor of the second and subsequent stitches is updated, but the first stitch may be updated to the third and subsequent stitches because there are many unstable factors. . Further, the predetermined minus upper thread amount S set for the first stitch may be used for the second and subsequent stitches.

Further, the release lever 39 is provided with a release cam 41 fixed to the upper shaft 2.
In the above, the holding and releasing of the upper thread of the yarn tension applying device 30 is shown, but the release lever 39 is operated by an electromagnetic actuator which operates at the detection phase detected by the upper shaft phase detecting means 69. You may do. Kimiaki Mami 58
A thread gripper operated by an electromagnetic actuator as shown in -14940 may be used.

Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, the upper yarn feeding device is the same as that of the first embodiment, and the resistance applying device for drawing out the insufficient yarn amount is different.

That is, in FIG. 11, the thread top 116 of the upper thread supply source which holds the upper thread 133, the upper thread feeding device 143, and the rotation amount detecting means 15
3. Since the upper thread holding device 156 is the same as that of the first embodiment, the description is omitted.

130 is a new thread tension applying device,
A thread tension setting dial 181 is rotatably supported on a dial shaft 182 fixed to the thread shaft 182. On the outer circumference of the thread tension dial, a thread tension indication "auto" for matching a thread tension indication mark (not shown) provided on the sewing machine frame 101,
The indications of “good” and “good” are provided, and a cam groove 181a centering on the dial shaft 182 is provided on the end face of the thread tension setting dial 181 corresponding to the indication.

The cam groove is the groove most the dial shaft 182 when the thread tension indication "OK" matches the thread tension indication mark.
The groove is formed so as to be the position furthest from the dial shaft 182 when the thread tension indication "Waiting" is matched with the thread tension indication mark at a position near the thread tension indication mark.

Reference numeral 183 denotes a slide plate which is formed in a plate shape and has a long groove 183 which is fitted on the dial shaft 182 and is movable in a plane portion.
a is provided. A pin 183b that can be fitted into the cam groove 181a is fixed to an end portion side of the long groove 183a of the slide plate. The end of the slide plate 183 is further bent to form a spring hook hole 183c.

Reference numeral 184 denotes a pressing lever, which is formed in a plate shape and has one end on a lever shaft 157 of the upper thread gripping device 156.
And is arranged on the gripping lever so as to be rotatable in the same manner as described above.

The other end of the pressing lever 184 is bent downward to form a guide 184a. A pressing spring 185 is disposed between the distal end of the pressing lever and a spring hook hole 183c at the distal end of the slide plate 183, and always rotates the pressing lever 184 counterclockwise to rotate the pressing lever. The guide portion 184a abuts on the grip lever 158 to urge the grip lever in a counterclockwise direction.
And the gripping spring 164 disposed between the gripping lever 158
Thus, the grip lever 158 rotating counterclockwise is pressed and further pressed by the urging of the pressing spring 185. A release lever 139 is a release cam (not shown) fixed to the upper shaft 2 as in the first embodiment.
11 are driven by the urging of a spring means (neither is shown), and are configured to move to two positions of a pull-out position indicated by a solid line and a feed-out position indicated by a two-dot chain line in FIG.

 Next, the operation of this embodiment will be described.

When descending from the top dead center of the balance, the feed dog 19
In the phase sunk from the upper surface of 18, i.e., the feeding phase, the required thread amount is theoretically calculated according to the sewing conditions, and the release lever 139 is moved from the drawing position shown by the solid line in FIG. 11 to the feeding position shown by the two-dot chain line. I do. The movement of the release lever abuts the tip of the guide portion 184a of the press lever 184, rotates the press lever 184 clockwise against the bias of the press spring 185, and grips the guide portion 184a. Release from lever 158. Therefore, the grip lever presses the driven rollers 162 and 163 against the drive roller 149 by the bias of the grip spring 164. The above-described calculation result is used to drive the upper thread payout stepping motor 147 so that the upper thread 133 is moved between the drive roller 149 and the driven rollers 162 and 163.
Is gripped and fed out. The payout is performed by the balance 115
Is fed out while the upper thread is in a relaxed state.

In the phase after the feeding is completed, the release lever 139 is retracted by the cam portion of the release cam to the position indicated by the solid line in the drawing and separates from the guide portion 184a of the pressing lever 184. Therefore, the pressing lever 184 rotates counterclockwise by the urging of the pressing spring 185, and the guide portion 184a of the pressing lever 184 contacts the gripping lever 158, and the pressing spring 1
By applying the bias of 85, the force for pressing the driven rollers 162 and 163 against the driving roller 149 is increased.

Since the above-mentioned amount of feeding is theoretically smaller than the necessary amount of thread as in the first embodiment, the insufficient upper thread is pulled out simultaneously with tightening of the seam by raising the balance 115. At this time, since the driving roller 149 is constituted by a one-way clutch similarly to the first embodiment, the driving roller 149 rotates without applying resistance to pulling out.
And 163 are strongly pressed by the urging force of the pressing spring 185, so that resistance is generated with respect to pulling out the upper thread 133, and the upper thread is pulled out in the same manner as in the first embodiment. .

The tension is adjusted by rotating the thread tension setting dial 181. In other words, when the "rotation" displayed on the outer periphery of the thread tension setting dial is rotated counterclockwise to match the thread tension instruction mark (not shown), the cam groove 181a slides to a position close to the rotation center. The pin 183b fixed to the plate 183 is guided, the slide plate moves in the long groove direction, and the spring hook hole 183c is moved to the dial shaft 182 side, and the guide portion 184a of the pressing lever 184 is provided.
The urging force of the pressing spring 185 for the driven rollers 162 and 163 to the driving roller 149 is increased by increasing the distance from the leading end.

The calculation of the feeding amount by the drive roller 149 and the formation of the stitches by other controls are the same as those in the first embodiment, and therefore the description thereof will be omitted.

Next, a third embodiment of the present invention will be described with reference to FIG.

In this embodiment, the yarn tension applying device and its releasing device are the same as those in the first embodiment, and the upper yarn gripping device is also the same as in the first embodiment. Means are different. That is, in FIG. 13, the construction of the thread top 216 of the upper thread supply source for holding the upper thread 233, the thread tension applying device 230, and the release lever 39 and the upper thread gripping device 256 are the same as those in the first embodiment, and therefore will be described. Omitted.

243 is a new needle thread feeding device, which is
01 Stepping motor 247 for needle thread feeding to holding plate 244
The delivery arm 286 is fixed to the output shaft 247a of the needle thread delivery stepping motor. A delivery pin 287 is fixed downward at the tip of the delivery arm.

288 is a stepping motor for feeding adjustment,
A feeding adjusting plate 289 is fixed to the output shaft 288a of the feeding adjusting stepping motor.

A pair of adjusting pins 290 are fixed to the feeding adjusting plate so as to face the feeding pin 287 and sandwich the feeding pin.

Reference numeral 291 denotes a rotating roller, which constitutes a one-way clutch that allows the support pin 245 fixed to the holding plate 244 to rotate only in the counterclockwise direction.

The configuration of this one-way clutch is described in the first section above.
Since it is the same as the drive roller 49 of the embodiment, detailed description is omitted.

Reference numeral 253 denotes a new rotation amount detecting means, in which a rotating body 293 is fitted to a pin 292 fixed to the rising portion 244a of the holding plate 244 so as to be rotatable and immovable in the axial direction. A rotating plate 254 having a plurality of slits is fixed to one end of the rotating body, and a photo interrupter 255 for detecting the amount of rotation in cooperation with the rotating plate is fixed to the holding plate 244.

An engagement arm 294 is rotatably fitted to the pair of rising portions 244b and 244c of the holding plate 244. The engagement arm 2
A pair of arms 294a and 294b of 94 are cylindrical portions 293a of the rotating body 293.
The arm 294 of the engagement arm 294 is arranged as shown in the figure.
The upper thread 233 guided below the a is the cylindrical portion 2 of the rotating body 293.
Threaded on 93a and then guided below the arm 294b of the engagement arm 294, the engagement arm being spring means (not shown)
Are engaged and are constantly urged downward to engage the upper thread with the cylindrical portion 293a of the rotating body 293 when the upper thread 233 is in a tensioned state. The body 293 is rotated so as to detect the amount of rotation between the rotating plate 254 and the photointerrupter 255, that is, the amount of the drawn-up thread.

 Next, the operation of this embodiment will be described.

When descending from the top dead center of the balance, the feed dog 19
In the phase sunk from the upper surface of the 18, that is, the feeding phase, theoretically the required amount of thread is calculated according to the set sewing conditions, and the release lever 239 moves following the rotation of the release cam 241. The release lever moves to enter between the thread tension plate 31 and the thread pressing plate 34 of the thread tension applying device 230 to move the thread pressing plate 34 in the axial direction, so that the thread tension plate 31 and the thread pressing A gap is generated between the upper thread 23 and the plate 34.
Release the pressure on 3.

The above-described calculation result is used to drive the upper thread feeding stepping motor 247 to rotate the feeding arm 286 fixed to the output shaft 247a counterclockwise.

The delivery pin 287 fixed to the tip of the delivery arm penetrates between the adjustment pins, and the upper thread 233 is drawn in between. The rotation roller 291 of the upper thread gripping device 256 is configured so as not to rotate clockwise with a one-way clutch in response to the pull-in.
2 and 263 are pressed by the bias of the gripping spring 264 to provide resistance to pulling in the upper thread from the balance side. On the other hand, since the thread tension applying device 230 releases the pressing on the upper thread 233 by the release lever 239, the upper thread is fed from the thread top 216.

After the feeding, the release lever 239 is rotated counterclockwise by the action of the release cam to release the pressing on the thread pressing plate 234. The thread pressing plate clamps the upper thread 233 between the thread tension plate and the thread tension plate 231 by pressing a thread tension spring (not shown).

After the pinching, the stepping motor 247 for feeding out the needle thread is performed.
And the delivery arm fixed to the output shaft 247a.
By rotating the 286 clockwise and retracting the payout pin 287 fixed to the tip from between the adjustment pins 290, the payout of the upper thread 233 is completed.

Using the result of the above-described calculation, the upper thread feeding device 243 is used.
The amount of yarn fed out is theoretically smaller than the required amount of yarn as in the first embodiment described above.
As a result, the insufficient upper thread is pulled out at the same time as tightening the seam. At this time, the rotation roller 291 is constituted by a one-way clutch similarly to the above-described first embodiment, and thus rotates without applying resistance to the thread being pulled out by the balance 215. On the other hand, the yarn tension applying device 230 holds the upper thread 233 between the thread tension plate 231 and the thread pressing plate 234 to apply tension. For this reason, the upper thread is pulled out from the thread top 216 under the same tension as in the first embodiment.

The calculation of the feeding amount by driving the needle thread feeding stepping motor 247 and the formation of the stitches by other controls are the same as those in the first embodiment, and therefore description thereof will be omitted.

In this embodiment, the position of the adjustment pin 290 is determined by the output shaft 288 of the unwinding adjustment stepping motor 288.
Since the adjusting plate 289 is configured to move by rotating the adjusting plate 289 fixed to a, the adjusting plate 289 is rotated in response to the counterclockwise rotation of the payout pin 287 driven by the needle thread feeding stepping motor 247. By rotating in the clockwise direction, the feeding amount can be increased. That is, it is possible to cope with the feeding under a condition that requires a large feeding amount during the high-speed operation.

In the above-described first to third embodiments, the method of detecting the withdrawal amount and newly setting the withdrawal amount has been described. It is also possible to feed out a small amount of the needle thread.

(Effect of the Invention) As described above, according to the present invention, it is theoretically difficult to detect and add a change from the sewing condition from the necessary thread amount corresponding to the change in the sewing condition, that is, the thread elongation characteristic, Calculate and supply the supply needle thread feed-out amount, which is reduced in advance by the specified amount in consideration of various conditions such as the difference in frictional resistance between the yarn and the cloth and the size of the through hole of the needle. Since the difference, that is, the shortage amount is configured to be applied from the upper thread supply source by applying the thread tension, it is difficult to detect and set most of the required upper thread amount by feeding without applying tension. Since the amount of thread is pulled out while pulling out the seam, a seam with good thread tightness can always be provided.
In addition, since the amount of yarn to be pulled out by applying the yarn tension is set to a very small value, the conventional yarn tension is adjusted only by the yarn tension. And an automatic thread tensioner corresponding to the sewing conditions can be provided.

[Brief description of the drawings]

The drawings relate to an embodiment of the present invention. FIG. 1 is a control block diagram of a sewing machine, FIG. 2 is an explanatory diagram of a needle thread feeding device, FIG. 3 is an external view of the sewing machine, and FIG. Explanatory diagram,
FIG. 5 is an explanatory view of the upper thread feeding portion, FIG. 6 is a front view of the cloth thickness detecting means, FIG. 7 is a side view of the cloth thickness detecting means, and FIG. FIG. 9 is an explanatory diagram of the operation, FIG. 10 is an explanatory diagram of a control state of a theoretically necessary amount of the needle and the amount of the upper thread paid out, FIG. 11 is an explanatory diagram of a second embodiment of the upper yarn feeding device, and FIG. FIG. 12 is an explanatory view of a third embodiment of the needle thread feeding device, wherein 15 is a balance, 17 is a needle, 20 is a shuttle which is a needle thread catching means, 30 is a thread tension applying device, and 43 is a needle thread feeding device. Reference numeral 47 denotes a stepping motor for feeding the needle thread, 49 denotes a driving roller, 62 and 63 denote driven rollers, 66 denotes a central processing unit, and 78 denotes a drive circuit which is a stepping motor control means for feeding the needle thread.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuru Nishijima 3-1-1 Kyobashi, Chuo-ku, Tokyo Inside Snake-no-Meg Sewing Machine Co., Ltd. (72) Inventor Akiyoshi Sasano 3-1-1 Kyobashi, Chuo-ku, Tokyo No. 1 Janome Eye Sewing Machine Co., Ltd. Examiner Hideaki Yoshizawa (56) References Japanese Utility Model Sho 58-112289 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) D05B 45/00

Claims (5)

(57) [Claims] A needle which moves up and down in conjunction with the rotation of an upper shaft, and a needle thread catching means for forming a lockstitch seam in cooperation with the needle;
In a sewing machine provided with a balance that moves up and down in synchronization with the up and down movement of the needle, the upper thread is intermittently arranged between the balance and the upper thread supply source in synchronization with the up and down movement of the needle. A yarn tension applying device for applying tension, a drive roller disposed between the yarn tension applying device and the balance, connected to a stepping motor for feeding the upper thread, and a driven roller contacting the drive roller. An upper thread feeding device for gripping the thread and feeding the upper thread from the upper thread supply source; calculating a theoretically necessary amount of the thread based on input values or detection values of sewing conditions; A sewing machine comprising: a calculating means for calculating a thread feeding amount; and a stepping motor control means for controlling a driving amount of the stepping motor for feeding the upper thread so as to correspond to a supply amount of the upper thread fed by a calculation result of the calculating means. Automatic needle thread feeding Location. 2. A driving roller of the needle thread feeding device is connected to an output shaft of the stepping motor for feeding the needle thread via a one-way clutch rotatable in a direction of feeding the upper thread of the output shaft. Claim (1)
5. The automatic needle thread feeding device of the sewing machine according to 4. 3. The sewing machine further comprises an upper shaft phase detecting means for detecting a rotation phase of the upper shaft, and the stepping motor control means detects the upper thread feeding stepping motor by the upper shaft phase detecting means. 2. An automatic upper thread feeding device for a sewing machine according to claim 1, wherein the repetition control of the excitation and the demagnetization is performed between the upper thread feeding phase and the upper thread feeding stopping phase of the upper shaft. 4. The apparatus according to claim 1, wherein said yarn tension applying device is configured to be capable of adjusting the tension. 5. The automatic thread feeding device according to claim 1, wherein said thread tension applying device applies tension by pressing said driven roller against said driving roller.